AssemblyAI Deploy Integration

Overview

Deploy AssemblyAI-powered transcription services to Vercel (serverless), Google Cloud Run (containers), and Fly.io with proper secrets management and webhook configuration.

Prerequisites

• AssemblyAI API key for production
• Platform CLI installed (vercel, gcloud, or fly)
• Application with working AssemblyAI integration

Instructions

Vercel Deployment (Serverless)

# Add secrets
vercel env add ASSEMBLYAI_API_KEY production
vercel env add ASSEMBLYAI_WEBHOOK_SECRET production

# Deploy
vercel --prod

API Route for Transcription:

// app/api/transcribe/route.ts (Next.js App Router)
import { AssemblyAI } from 'assemblyai';
import { NextRequest, NextResponse } from 'next/server';

const client = new AssemblyAI({
  apiKey: process.env.ASSEMBLYAI_API_KEY!,
});

export async function POST(req: NextRequest) {
  const { audioUrl, features } = await req.json();

  if (!audioUrl) {
    return NextResponse.json({ error: 'audioUrl required' }, { status: 400 });
  }

  // Use submit() + webhook for production (non-blocking)
  const transcript = await client.transcripts.submit({
    audio: audioUrl,
    webhook_url: `${process.env.NEXT_PUBLIC_APP_URL}/api/webhooks/assemblyai`,
    webhook_auth_header_name: 'X-Webhook-Secret',
    webhook_auth_header_value: process.env.ASSEMBLYAI_WEBHOOK_SECRET!,
    speaker_labels: features?.speakerLabels ?? false,
    sentiment_analysis: features?.sentiment ?? false,
  });

  return NextResponse.json({
    transcriptId: transcript.id,
    status: transcript.status,
  });
}

Webhook Handler:

// app/api/webhooks/assemblyai/route.ts
import { AssemblyAI } from 'assemblyai';
import { NextRequest, NextResponse } from 'next/server';

const client = new AssemblyAI({
  apiKey: process.env.ASSEMBLYAI_API_KEY!,
});

export async function POST(req: NextRequest) {
  // Verify webhook authenticity
  const secret = req.headers.get('x-webhook-secret');
  if (secret !== process.env.ASSEMBLYAI_WEBHOOK_SECRET) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  const { transcript_id, status } = await req.json();

  if (status === 'completed') {
    const transcript = await client.transcripts.get(transcript_id);
    // Store transcript, notify user, trigger downstream processing
    console.log(`Transcript ${transcript_id} completed: ${transcript.text?.length} chars`);
  } else if (status === 'error') {
    console.error(`Transcript ${transcript_id} failed`);
  }

  return NextResponse.json({ received: true });
}

Vercel config:

{
  "functions": {
    "app/api/transcribe/route.ts": { "maxDuration": 60 },
    "app/api/webhooks/assemblyai/route.ts": { "maxDuration": 10 }
  }
}

Google Cloud Run Deployment

FROM node:20-slim
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY . .
EXPOSE 8080
CMD ["node", "dist/server.js"]

# Store secret in Secret Manager
echo -n "your-api-key" | gcloud secrets create assemblyai-api-key --data-file=-

# Build and deploy
gcloud builds submit --tag gcr.io/$PROJECT_ID/assemblyai-service

gcloud run deploy assemblyai-service \
  --image gcr.io/$PROJECT_ID/assemblyai-service \
  --region us-central1 \
  --platform managed \
  --set-secrets=ASSEMBLYAI_API_KEY=assemblyai-api-key:latest \
  --allow-unauthenticated \
  --memory 512Mi \
  --timeout 300

Fly.io Deployment

# fly.toml
app = "my-assemblyai-app"
primary_region = "iad"

[env]
  NODE_ENV = "production"
  PORT = "3000"

[http_service]
  internal_port = 3000
  force_https = true
  auto_stop_machines = true
  auto_start_machines = true
  min_machines_running = 1

fly secrets set ASSEMBLYAI_API_KEY=your-api-key
fly secrets set ASSEMBLYAI_WEBHOOK_SECRET=your-webhook-secret
fly deploy

Streaming Token Endpoint (All Platforms)

// Endpoint to generate temporary tokens for browser streaming
// Works on any platform — the key is to never expose your API key to the client

import { AssemblyAI } from 'assemblyai';

const client = new AssemblyAI({
  apiKey: process.env.ASSEMBLYAI_API_KEY!,
});

export async function GET() {
  const token = await client.streaming.createTemporaryToken({
    expires_in_seconds: 300,
  });

  return Response.json({ token });
}

Health Check (Platform-Agnostic)

import { AssemblyAI } from 'assemblyai';

const client = new AssemblyAI({
  apiKey: process.env.ASSEMBLYAI_API_KEY!,
});

export async function GET() {
  const start = Date.now();
  try {
    await client.transcripts.list({ limit: 1 });
    return Response.json({
      status: 'healthy',
      assemblyai: { connected: true, latencyMs: Date.now() - start },
      timestamp: new Date().toISOString(),
    });
  } catch {
    return Response.json({
      status: 'degraded',
      assemblyai: { connected: false, latencyMs: Date.now() - start },
      timestamp: new Date().toISOString(),
    }, { status: 503 });
  }
}

Output

• Application deployed with AssemblyAI secrets securely configured
• Webhook endpoint for async transcription notifications
• Streaming token endpoint for browser clients
• Health check endpoint monitoring AssemblyAI connectivity

Error Handling

Issue	Cause	Solution
Secret not available at runtime	Wrong env name or missing secret	Verify with platform CLI
Webhook not receiving events	URL not publicly accessible	Verify URL, check firewall/CORS
Function timeout (Vercel)	transcribe() takes too long	Use submit() + webhook pattern
Cold start latency	Serverless spin-up	Set minimum instances or use submit()

Resources

• Vercel Environment Variables
• Cloud Run Secrets
• Fly.io Secrets
• AssemblyAI Webhooks

Next Steps

For webhook handling, see assemblyai-webhooks-events.